Various kinds of position pointers for use with a position detection sensor have been proposed. For example, in Patent Document 1 (Japanese Patent Laid-Open No. Hei 7-295722) and Patent Document 2 (Japanese Patent Laid-Open No. Hei 8-272509), a coordinate inputting apparatus is disclosed, in which a position pointer includes a generator of an AC signal and a battery as a driving power supply such that the position detection sensor detects a signal in response to the AC signal transmitted from the position pointer to thereby detect the position of the position pointer.
Further, Patent Document 3 (Japanese Patent Laid-Open No. 2007-183809) discloses a position pointer, which includes a switching circuit capable of switching a state of a conductor at a pen tip between a signal reception state and a signal transmission state to thereby form a signal processing circuit having a so-called half-duplex communication configuration, and a battery as a driving power supply.
In the position pointer of Patent Document 3, the switching circuit is changed over (switched) between the signal reception side and the signal transmission side after each predetermined time period by a timing controlling circuit. During signal reception, a conductor at a pen tip receives an AC signal from a position detection sensor, and another AC signal synchronized with the received AC signal is produced by the signal processing circuit. Then, during a period in which the switching circuit is switched to the signal transmission side, the AC signal produced by the signal processing circuit is transmitted to the position detection sensor from the pen tip conductor, which has received the AC signal from the position detection sensor. The position detection sensor detects the signal from the position pointer, thereby detecting the position of the position pointer.